From 196847af157ed271ee10530a92afea7b7e44c865 Mon Sep 17 00:00:00 2001
From: Chiwon Cho <superdoli@gmail.com>
Date: Wed, 11 Nov 2020 20:12:40 +0900
Subject: [PATCH] Apply dummy last key to VarDB

* Add DUMMY to KeyType class
---
 iconservice/iconscore/db.py                |  4 +++-
 iconservice/iconscore/icon_container_db.py | 10 +++++++---
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/iconservice/iconscore/db.py b/iconservice/iconscore/db.py
index 0f7d308b0..b0e67b66c 100644
--- a/iconservice/iconscore/db.py
+++ b/iconservice/iconscore/db.py
@@ -46,6 +46,7 @@ class KeyType(Enum):
     SUB = auto()
 
     ARRAY_SIZE = auto()
+    DUMMY = auto()
     LAST = auto()
 
 
@@ -170,7 +171,8 @@ def _get_container_final_key_with_pipe(self, last_key: Key) -> List[bytes]:
                 keys.append(self._tag.value)
             keys.append(key.value)
 
-        keys.append(last_key.value)
+        if last_key.type != KeyType.DUMMY:
+            keys.append(last_key.value)
 
         return keys
 
diff --git a/iconservice/iconscore/icon_container_db.py b/iconservice/iconscore/icon_container_db.py
index 0156095b6..7d6c3819c 100644
--- a/iconservice/iconscore/icon_container_db.py
+++ b/iconservice/iconscore/icon_container_db.py
@@ -284,6 +284,7 @@ class VarDB(object):
     :K: [int, str, Address, bytes]
     :V: [int, str, Address, bytes, bool]
     """
+    _DUMMY_LAST_KEY = Key(b"", KeyType.DUMMY)
 
     def __init__(self, var_key: K, db: 'IconScoreDatabase', value_type: type) -> None:
         # Use var_key as a db prefix in the case of VarDB
@@ -297,7 +298,7 @@ def set(self, value: V) -> None:
         :param value: a value to be set
         """
         byte_value = ContainerUtil.encode_value(value)
-        self._db.put(b"", byte_value)
+        self._db.put(self._DUMMY_LAST_KEY, byte_value)
 
     def get(self) -> Optional[V]:
         """
@@ -305,13 +306,16 @@ def get(self) -> Optional[V]:
 
         :return: value of the var db
         """
-        return ContainerUtil.decode_object(self._db.get(b""), self.__value_type)
+        return ContainerUtil.decode_object(
+            self._db.get(self._DUMMY_LAST_KEY),
+            self.__value_type
+        )
 
     def remove(self) -> None:
         """
         Deletes the value
         """
-        self._db.delete(b"")
+        self._db.delete(self._DUMMY_LAST_KEY)
 
 
 def get_default_value(value_type: type) -> Any: